Engine starter



Filed Aug. 27, 1928 2 Sheets-Sheet l Aug. 8, 1933. R. CHILTON 1,921,344

ENGINE STARTER Filed Aug. 27, 192s 2 'sheets-sheet 2 de @dit mesne assignments, to Eclipse Machine (Cornu pany, lillrnira liileiglbts, N, EL, a Corporation of implication/ingest 233 della, No., @2,296

d Claima invention relates to engine starters adapt ed for utilizing fluid pressure as from. air pre= compressed into a reservoir or from an explosive cartridga the latter embcdnnent being illustrated in the preferred showing of the drawings.

Ojne object of the invention is to provide a sirn-1 ple, compact and easily fabricated device for den riving several revolutions such as needed for starting an internal combustion engine from a relatively short single stroke of -a fluid operated piston.

ltfiany uid pressure starters of the prior art involve the piercing of each engine cylinder for installation oi non-return valves which are individually piped to a continuously engine driven f distributor, and they also require an engine driven compressor; and a failure in any one of these parts is aptto cause an. engine failure. An important object of the present invention is to provide a iiuid pressure starter which avoids I by means of cartridges of slow burning powder or highly pre-compressed gas such as air, and the invention provides simple and light means for practically applying such energy to the starting of an engine.

The invention' may also be used in connection with a larger reservoir containing suicient compressed air for several starts, but in the preferred embodiment .individual cartridges each containing enough potential energy for one start are utilized. In either' case, however, the power piston and its associatedengine rotating mechanism will be substantially the same type and will comprise one unit of the machine. The other unit which may be located at any convenient distance, consists in the preferred embodiment, of a breech chamber into which the cartridges may be introduced for discharge of their energy to the piston. The two units are connected by a pipe of suitable length to bring the breech convenient tothe hand of the operator for introducing the cartridges of which a supply may be carried inl a suitable holder.

Various other objects and advantages of the inventionwill be in part obvious from. an inspection of the accompanying drawings and a cares ful consideration of the following particular description and claims-of one form of mechanism embodying my invention.

in the drawings: v

`iiigure l is a longitudinal section oi the piston and engine starting gear unit of the present invention.

l'ligure 2 isla longitudinal section of the breech chamber-portion of the invention drawn on a slightly smaller scale tlianFi'ga l. Y

With reference to the drawings, and more par= ticularly to Fig. l, the piston and engine staining gear unit comprises a body member lo having a flange l2 by which it is secured to the engine crankcase i3 as by bolts le, the :dange being conE veniently of a size standardized :for aircreit en'A gine starters. The engine crankshaft, or ether drive shaft (not shown) is provided with an enx1 gine jaw ll engageable by the starter jaw i5 as Will be later more iully described..

Screw threaded in a quickly detachable manner to an annular flange 16 integral with the body 10 is a cylinder 17 having a closed head le,

the cylindrical piston body 20. This piston body 20 and the main starter body l() are provided with co-operating helical grooves 2i and 22 which are placed a series oi anti-friction members shown as balls 23, suitable stops 2d being provided at each end of each helical groove to prevent the balls from excessive movement. A jaw sleeve 26 is internally drivably connected with the piston body 20 by Asplines 27 and 28 which permit the axial travel of the piston relative to the sleeve, but restrain these two parts to unitary rotation. An anti-friction thrust bearing 2e is preferably interposed between the end di the sleeve 2d and a nose piece 30.

The starter jaw l5 is splined for limited axial travel within the sleeve 26 and is normally retained in the position shown by a spring 25 abut-- ting the plate 3l held in position by the, central rod 32 which is connected to the jaw l5 as by the nut 33 and shoulder 3d.

This rod has a piston nt within the bore of a l sleeve 35 which is integral withAthe-piston head 19, the end of the rod being exposed to the gas pressure within the cylinder 17.

Exhaust ports 36 are uncovered by the piston at the left hand end of its stroke and an exhaust ring 37 preferably collects the discharge so that it may be led away to any desired point by a suitable pipe 38. A spring 39 normally maintains the piston at the right hand end of its travel as shown, and the piston is preferably equipped With a relatively thin .endless packing ring 40 pressed against the cylinder wall by.a split spring piston ring 41. A displacement ring 43 retains the packing ring in position by means of the screws 44 and has a close t over a projection 45 of the main body 10 between which projection and the cylinder wall 17 the displacement ring 43 constitutes an annular piston adapted to arrest the starter piston 20 at the inner end of itsl stroke in a cushioned manner by means of compression of the entrapped air. The cylinder head 18 is provided with a pipe 46 which may be connected to the breech or other pressure chamber.

The operation of the mechanism so far described is as follows:

Upon pressure being generated and released from the pressure chamber 47 by a pressure element such as an explosive cartridge 48, the high pressure uid is conveyed by means of the pipe 46 to the cylinder 17, and acts both upon the piston head and the central rod 32. There being practically no resistance other than the spring 25 to the movement of the rod, it is instantly advanced to the left thus engaging the engine jaw 11 and at the same time the piston 9 advances, and enforces a rotary motion on the starter jaw due to the helical grooves 21 and 22 and the antifriction members 23. The engine is accordingly turned over and when the piston reaches a point where the exhaust ports 36 are uncovered the fluid pressure will escape and the spring 39 can return the piston to the normal position shown in the drawings. At whatever point of the piston travel the engine starts under its own power, it is free to overrun the jaws 15 due to their sloped or angular formation, and the spline connection of the A jaw with the sleeve 26.

Since internal combustion engines start oli relatively suddenly, the conclusion of the starter piston stroke may be at relatively high speed and an air dash pot for arresting the piston Without shock, after the ports 36 have been passed, is provided by the annular displacement ring 43 which compresses air in the annulus between the projection 45 and the cylinder 17.

During its travel the piston body slides over the jaw sleeve 26 by means of the splines 27 and 28 which transmit the starting torque generated from the piston thrust by the helical groove connection, and the friction produced may impose considerable axial pressure on the sleeve 26. The antifriction ball bearing 23 takes such friction re-actions which might otherwise impose too much restraint to the return action of the spring 39.

Due to the screw thread connection lbetween the cylinder 17 and the body flange 16, the former may be quickly detached for removing any fouling that may'occur where combustible cartridges are used.

One of the objects of this invention is to obtain a relatively large number of l,turns from a relatively short piston travelI wherefor a relatively short lead or helix angle is used for the main driving threads 21 and 22 and therolling anti-friction members 23 are introduced to insure high mechanical eiciency in spite of this small angle of helix.

When thepreferred cartridge 48 is used, it is desirable to so adjust theI capacity and rate of pressure development that the pressure Will remain as nearly constant as practical until the piston approaches the exhaust ports whereupon further development of energy should stop. Excessive noise and fire risk may be eliminated by the attachment of a suitable muliler to the exhaust pipe 38. A safety valve for the pressure chamber 47 may be provided such as shown in Fig. 2, said safety valve comprising a tubular member 49 provided with a plurality of ports 50, and a ball 51 piston adapted for axial advance, helical means associated with the piston to produce rotation thereof from said advance, an engine engaging member rotatable with the piston, and means for moving said engine engaging member longitudinally but independently of saidpiston, said last named means and said piston being disposed so as to be simultaneously subjected to the pressure of an actuating fluid.

2.In a starter for an engine having an engageable starting member, the combination comprising a piston operable by fluid pressure, an-engaging member driven rotatably from the piston and adapted to engage the engine member, means extending into position to be subjected to the fluid pressure which operates upon said piston and thereby move the engine engaging member into driving engagement with said' engine member, the fluid pressure being effective upon both said piston and last named means simultaneously, and helical means adapted to impress a rotary motion upon the engaging member when the piston is advanced.

3. In a starter for an internal combustion engine, the combination of a cylinder secured to a portion of said engine, a rotatable piston within said cylinder. adapted for' axial movement relative thereto, helical means adapted to cause rotation of said piston as it is advanced axially, an engine engaging member drivably connected to said piston for rotation therewith and adapted for independent axial movement relative thereto in response to fluid pressure, and means for causing such axial movement of said engine engaging member, said last named means including a part having a surface disposed in relation to said piston so that both said surface and piston simultaneously receive the pressure of the actuating fluid.

4. In an engine starter, the combination with a source of fluid pressure, of a cylinder connected to said source of pressure and having an internally threaded surface, an exteriorly threaded piston in said cylinder, meansfor operatively connecting the threads of the piston and cylinder whereby longitudinal movement of the piston relative to the cylinder is converted into a rotary movement of said piston, an engine engaging member drivably connected to said piston and mounted for longitudinal movement independently thereof, a pressure actuated rod carried by` the piston and operatively connected to the engine engaging member for moving the latter longitudinally, and means for simultaneously sub-'i jecting said piston and rod to the pressure of the fluid entering said cylinder from said source.

5. In a starter for an internal combustion engine, the combination'of a cylindersecured to a portion of said engine, a. piston Within said cylinder adapted lfor axial movement relative thereto in response to iiuid pressure, helical means adapted to cause rotation of said piston as it is advanced by the uid pressure, an engine engaging member drivably connected to said piston for rotation therewith and adapted for independent axial movement relative thereto in response to uid pressure, means including a part having a. surface adjacent the uid pressure receiving surface of said piston, said part being movable by said fluid 4pressure to cause axial movement. of said engine engaging member, and means for exhausting the pressure fluid from said cylinder as said piston approaches the limit of its axial movement.

6. In an engine starter, the combination with a source of fluid pressure, of a cylinder connected to said source of pressure and havinganinternally threaded part, a piston reciprocable in said cylinder, an externally threaded sleeve mounted for movement axially with said piston, and also rotarily through engagement of its threads with those of said internally threaded part, an engineengaging member drivably connected to said sleeve and capable of longitudinal movement into cranking position as Well as rotary movement with said sleeve, and pressure actuated'means carried by said piston and subjected to the pressure of the fluid which acts simultaneously upon said piston for effecting such longitudinal movement of said engine-engaging member.

ROLAND CHILTON.

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